With Ruby Sass being deprecated and unmaintained as of March 26 2019, this gem will no longer be something you should depend on.

As a replacement, you could try building custom color classes using Sass with something like the following.

Add to your colors file a map of all colors.

/* My Colors File */
$black: #000;
$white: #ffffff;
$light_gray: darken($white, 20%);
$dark_gray: lighten($black, 20%);

/** Map of colors **/
$all_colors: (
  "black": $black,
  "white": $white,
  "light_gray": $light_gray,
  "dark_gray": $dark_gray
);

Then you can generate classes for your palette with something like

@each $name, $color in $all_colors {
  .palette-colors__color--#{$name} {
    background-color: #{$color};
  }
}

And in your view you'll need to add a duplicate list of these colors with something like

# app/views/palettes/show.html.slim
ruby:
  colors = %w( black white light_gray dark_gray )

.palette-colors
  - colors.each do |color|
    .palette-colors__color class="palette-colors__color--#{color}"
      .palette-colors__color-info
        .palette-colors__color-info__name = color

This will no longer show the value, though I'm sure you could figure that out with some more SCSS interpolation.

For more reading: Ruby Sass is Deprecated

This dirt simple Gem uses the Sass ruby library to read your colors.scss file and give you back a list of color names and their actual colors which can be used to generate a nice color palette page in a Rails app.

If you are using Bootstrap and overriding Bootstrap colors, this Gem will probably not work for you. It requires that all color definitions are made in a single file. Perhaps in the future it will follow @imports.

Add this line to your application's Gemfile:

gem 'sass-color-extractor'

And then execute:

$ bundle

Or install it yourself as:

$ gem install sass-color-extractor

You should extract your color variables into their own file (which you would then @import as necessary in your scss/sass files. Once you have that, you can get a map of color names to their hex color like so:

scss_file = "/path/to/my/colors.scss"
pp SassColorExtractor.parse_colors(scss_file)

For a more concrete example, given this colors.scss file

/* My Colors File */
$black: #000;
$white: #ffffff;
$light_gray: darken($white, 20%);
$dark_gray: lighten($black, 20%);

You'd get a hash in ruby like this:

{
  "black"=>"000",
  "white"=>"ffffff",
  "light_gray"=>"cccccc",
  "dark_gray"=>"333333"
}

To add a page in your Rails app that shows all the colors defined in the palette with their corresponding hex value, add a route, controller and view:

# config/routes.rb

MyApp::Application.routes.draw do
  ...
  resource :palette, only: [:show]
end

# app/controllers/palettes_controller.rb
class PalettesController < ApplicationController
  def show
    f = File.expand_path('app/assets/stylesheets/_colors.scss')
    @colors = SassColorExtractor::Base.parse_colors(f)
  end
end

# app/views/palettes/show.html.slim
.palette-colors
  - @colors.each do |name, hexval|
    .palette-colors__color(style="background-color: ##{hexval}")
      .palette-colors__color-info
        .palette-colors__color-info__name = name
        .palette-colors__color-info__hexval = "##{hexval}"

With a little CSS:

// app/assets/stylesheets/palette.scss
.palette-colors {
  display: flex;
  flex-flow: row wrap;
  justify-content: center;
}
.palette-colors__color {
  border-radius: 4px;
  border: 1px solid #ddd;
  margin: 7px;
  width: 120px;
  height: 120px;
  position: relative;
}
.palette-colors__color-info {
  position: absolute;
  bottom: 0px;
  width: 100%;
  padding: 4px;
  text-align:center;
  background-color: rgba(200,200,200,0.7);
  font-size: 0.8rem;
  border-radius: 4px;
  color: #000;
}

You should get a nice little palette.

1. Fork it ( https://github.com/rcode5/sass_color_extractor/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request